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Mr. Charles Miller,USA Gasoline Corporation November 6, 2006 <br /> Baseline Site Investigation Report Project No.2007-3756-01 <br /> USA Station No. 3756, Lockeford,California <br /> Page 3 <br /> Analytical Methods <br /> Soil samples were forwarded to Alpha Analytical, Inc., a California state-certified <br /> laboratory (ELAP #2019), for chemical analysis under strict chain-of-custody procedures. <br /> The samples were analyzed for gasoline range organics (GRO) using USEPA Method <br /> SW8015B DHS/LUFT Manual, and for benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX), methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), tertiary <br /> butyl alcohol (TBA), ethyl tertiary butyl ether (ETBE), and di-isopropyl ether (DIPE) using <br /> USEPA Method SW8260B. Soil analytical results are presented in Table 1. Certified <br /> analytical reports with chain-of-custody records are presented in Appendix B. <br /> FINDINGS <br /> Site Geology <br /> Sandy soils were generally observed from surface grade to depths ranging from <br /> approximately 25 to 30 feet bgs. Silty soils, approximately 3 feet in thickness, appear to be <br /> interbedded within the sandy strata at depths ranging from approximately 13 to 17 feet bgs. <br /> A laterally continuous interval of clayey silt and silty clay, approximately 5 to 13 feet in <br /> thickness, was observed at each boring location at depths ranging from approximately 25 to <br /> 43 feet bgs. Sandy soils underlie these clayey silt/silty clay soils to 50 feet bgs, the <br /> maximum depth explored during this phase of investigation. Groundwater was not <br /> encountered in any of the soil borings. <br /> Soil Analytical Results <br /> Petroleum hydrocarbon and fuel additive concentrations were not reported above <br /> laboratory detection limits in any of the soil samples collected during this phase of <br /> investigation. <br /> SUMMARY <br /> The following summarizes the findings of the investigation: <br /> • Sandy soils were predominately observed in the subsurface from surface grade to <br /> 50 feet bgs. Laterally continuous clayey silt/silty clay soils, approximately 5 to 13 <br /> feet in thickness, were observed at depths ranging from approximately 25 to 43 <br /> feet bgs. <br /> • Groundwater was not encountered during the investigation. <br /> • Concentrations of petroleum hydrocarbons and fuel additives were not reported <br /> above laboratory detection limits in any of the soil samples. <br /> KAUSA Gaso1ine\3756\Reports\USA 3756-baseline assessment report.doc STRATUS <br />